An aircraft conventionally has at least one propulsion system, comprising a nacelle inside which there is disposed an engine, for example of the turbojet type, and which is fixed to the structure of the aircraft by way of a mast fixed beneath the wing of the aircraft.
In order to prevent damage to the structure of the aircraft when an engine catches fire, the aircraft conventionally has, for each nacelle, two tanks containing an extinguishing fluid, which can be a liquid or gaseous agent.
FIG. 1 is a schematic illustration of a prior art propulsion system, comprising a nacelle 16 and an engine 17 disposed inside the nacelle 16. This nacelle 16 is fixed beneath the mast 12 extending beneath the wing 14 of the aircraft.
In order to detect the onset of a fire in the propulsion system, the system is provided with a plurality of fire sensors 18, which are distributed within the propulsion system and which are connected to a detection unit 20.
For each propulsion system, the aircraft carries two tanks 22a and 22b, generally spherical in shape, which are fixed to the mast 12, are provided with explosive cartridges 23a-b, and are filled with an extinguishing fluid.
A network of pipes 24 extends between each tank 22a-b and different zones of the propulsion system.
When a fire sensor 18 detects a fire in the propulsion system, it informs the fire detection unit 20, which triggers a warning means present in the cockpit. The pilot then actuates an activation button, which actuates the explosion of one of the explosive cartridges 23a-b so as to release the extinguishing fluid from the associated tank 22a-b, the fluid then permeating the propulsion system through the network of pipes 24.
An anti-fire system of this type is fully satisfactory, but the extinguishing fluid used is generally based on bromotrifluoromethane, also referred to as “halon.” Because this product is a relatively polluting product, it is being phased out and replaced increasingly by other products. These new products require tanks that have greater holding capacities, and these increases are not always compatible with the space available at the mast, which is already a relatively crowded zone.